A pack of monsters calling themselves the "Clan of the Seafolk" arrive on the shores of City J intent on invading the land. When the hero sent to fight them is defeated easily by the Deep Sea King himself, Saitama and Genos head for the city to help.
So that no hero ever dies in vain,
،ولكي لا يموت أيّ بطلٍ هباءً
Afin d’éviter des morts vaines,
ils devraient tous
Per evitare che altri eroi muoiano invano,
d'ora in poi...